Do you have all of the JARs you listed downloaded and placed in the EXT folder? Doing a quick google search of the message you shared, you may be missing the "ooxml-schemas" jar still.
I have placed the below jar files in EXT folder:
Okay, I was reading up a bit more. You can also try placing them in the \Smartbear\ReadyAPI\LIB folder too, and restarting ReadyAPI. I apologize for my confusion earlier on folders.
I have seen other posts here on the forum that reference a jar file called "ooxml-schemas-1.3.jar" so you may try renaming the jar file or making a copy where "poi-" is not part of the name. I am not 100% sure though. I'll see if I can do some troubleshooting later today if you still have an issue.